Chicken Pox Causes and Risk Factors

Causes of chicken poxChicken pox is directly caused by the varicella-zoster virus, a member of the herpes virus family. Additionally, chicken pox spreads very easily from one person to another. The virus is spread through direct contact with skin lesions, oral secretions or via the air. More precisely, the virus is transmitted by direct contact with the rash or by droplets dispersed into the air by coughing or sneezing. The disease spreads quickly, especially in places of close contact (schools, families, or child care).

Risk factorsPeople at risk of contracting chickenpox include anyone who hasn't been vaccinated or who has never had the disease. People who've been vaccinated against chickenpox are usually immune to the virus. The same is true of anyone who has had chickenpox in the past.

People who have not contracted chicken pox

People who have not been vaccinated for chicken pox

Infants under the age of one people over fifteen are at greater risk for complications associated with chickenpox than otherwise healthy children. People with weakened immune systems or pregnant women who have never contracted the virus also are at greater risk for severe illness and complications.

Most chicken pox infections occur from March to May in children under age 15. However, older children and adults can also contract chicken pox. But how can you know if you exhibit signs or symptoms of chicken pox? And when should you seek medical help? Learn more about symptoms of chicken pox in the Chicken Pox Symptoms section that follows.

This document was last reviewed by on 10/01/2009.
This information is not intended
to replace the medical advice of your doctor or health care
provider. Please consult your health care provider for advice
about a specific medical condition.